Hopefully somneone can help here. Before installing my Wolf stand alone engine management system the car ran okay. The guy installing my stand alone fixed boost leaks through out the system. Now that the car has no boost leaks the car has an issue. The car runs fine up until 4000 RPMs. At this time the boost starts acting up. It will fluctuate from 15 lbs to 5 lbs on my gauge. The wastegate has been removed and tested with a good unit and the problem still occurs. The blow off valve is in working order. The last thing my mechanic could think of, after testing everything else, was that the turbocharger may have problems. Even with this problem the car has dynoed at 300 RWHP. Is this HP still possible with a turbo that may need to be rebuilt? Could the turbo act normally up until 4000 RPMs and then totally crap out once reaching this threshold? I just don't want to spend the extra cash since my turbo was working fine before. Of course I had boost leaks in many places before. Maybe this is why this problem never surfaced even at the track above 4000 RPMs. Any thoughts or advice would be appreciated. Thanks.

Ignacio

 

What kind of wastegate and controller?

Chris White

 

A LR dual port wastegate and a boost valve which the installer of my Wolf uses on his race car and other locals. Sorry I don't know the specifics on the boost controller. All I know is that boost is controlled with the Wolf through this valve.

 

My first thoughts are to look at was has been changed. The boost was fine before. Now with the Wolf and new contol valve there are problems. Does the wolf show you the duty cycle of the control valve(like the AVC-R does)? That might tell you if it is even opening the wastegate when it should. Do you have MBC or a seperate EBC you could install and see if it's any better? Or you could unplug the wastegate vacuum and carefully drive to 4k and see if the wastegate spring alone can give steady boost. If that's the case it is surely a controller issue.

A bad turbo would make noise, blow oil, etc. I don't see how a bad turbo could only fluctuate boost without having other very obvious issues

btw, I am very happy with the Stage 4 MAF I bought from you, thank you! If you get sick of the Wolf and uhhhh ever wanna go back to your old system I'll happily trade haha

 

I'd guess it is a controller issue too. My APexi did exactly the same thing before I ripped it out. Might be interesting to monitor the control signal going to the WG (with a boost guage?) to see what the WG is seeing.

You say you make 300rwhp -- I trust you can feel the boost surging and falling, such that it is not as simple as a faulty gauge, right?

 

eniac: I am glad that the Stage IV MAF is working well for you. I'll have to think about that trade.

eniac and Tom M'Guinn: I don't think it is the boost controller. He has checked this as well.

Tom M'Guinn: I have not been on the dyno when this is happening but the guy working on the install has. I trust his diagnosis.

I have spoken to a very reputable turbo builder on the 993 turbo forum and he said that I may have oversped the turbocharger with all of the boost leaks I previously had. This would accelerate the wear of the bearings and could even have compressor wheel rub. Thus the lack of boost at 4K. Of course he can't judge the condition of the turbo until I take it over to him.

 

when my wastegate was installed backwards it did that.

 

emwporsche: It isn't the wastegate. He has removed the LR wastegate and replaced it with stock workable units and the same problem persists.

 

collapsed downpipe maybe?

 

Try bypassing the boost controller, use a MBC
& see what happens.

 

I used to get something similar when I was using a K26/8 / SBC-ID / LR DPW.

When the boost was set to anything over 15 psi, it used to oscillate between say 18 and 10.

Solved it by adjusting the gain settings on the SBC-iD.

HTH

Rick
(Still waiting form my Wolf-3D)